Lubrication control



J1me 1946- A. s. THOMPSON 2, 67

LUBRICATION CONTROL Filed Jan. 31', 1944 3 v mvENTok fl/bertd'. 7710mpson BY [film ATTohNEY reamed June 18, 1946 women-non coN'moL Albert S. Thompson; Primos, Pm, assignor to Westinghouse Electric Corporation,

East Pittsburgh, Pa a corporation of Pennsylvania Application January 31, 1944, Serial No. 520,488

11 Claims. 1

This invention relates to gas turbines and particularly to an improved lubricating and scavenging system. therefor, and it ha for an object to provide an improved system of the character set forth.

In connection with lubrication of the bearings of a gas turbine, leakage of lubricating oil during shutdown and starting periods and consequent danger of fire particularly when stopping and starting makes it desirable to remove such oil as remains in the bearing and which would 1oitherwise leak therefrom during a shut-down pe- In accordance with thepresent invention, the lubricating oil is scavenged from the bearings, and preferably from the oil cooler and pipes connecting the cooler to the bearings, when the plant is shut down to prevent the accumulation of oil in the flow passage of the power plant and which might result in a serious fire hazard. Accordingly, a further object of the invention is to provide apparatus effective for this purpose.

These and other objects are effected by the invention as will be apparent from the following description and claims taken in connection with the accompanying drawing, forming a part of this application, in which:

Fig. 1 is a side elevational view of a gas turbine power plant in which the present invention is incorporated;

Fig. 2 is a schematic diagram of the lubricating system and oil scavenging system of the plant shown in Fig. l, and

Fig. 3 is a detail view, partly in section, illustrating a modification which may be employed in the present invention. I

The gas turbine power plant shown in Fig, 1 is particularly adapted for use in propelling aircraft although it is to be understood that the invention is not limited to this particular use. The plant shown in Fig. 1 is preferably constructed in accordance with the disclosure in the copending application of Stewart Way, Serial No. 482,533, filed April 10, 1943 and assigned to the assignee of the present invention. The power plant in general comprises an outer tubular casing in of streamline section and an axial core structure, generally indicated H, defining, with the tubular casing, an annular flow passage l2. The flow passage l2 extends fore and aft with respect-to the aircraft in which the plant is mounted with the left or inlet end l3 of the passage, as viewed in Fig. 1, pointed in the direction of flight.

The core structure ll comprises a front fairing cone l4 adapted to house fuel and lubricating pumps and other auxiliaries (not shown) an axial flow compressor IS, a combustion chamber It, a gas turbine I! and an axially. movable tailpiece l8 which defines with the rear of the casing l0 an adjustable annular propulsion nozzle l9. s

The plant operates generall a follows: Air enters atthe inlet I3, is compressed by the com- -press0r l5 and flows into the combustion chamber l6 where it is mixed with fuel and ignited. The resulting hot motive'fluid comprising the products of combustion and excess air driv the turbine I! which extracts at least suflicient power from the motive fluid to drive the compressor I 5 and the mentioned pumps and auxiliaries. The motive fluid is discharged through the propulsion nozzlev l9 as a reaction jet to propel the aircraft.

A lubricating oil pump 2!, as well as the rotors of the compressor l5 and turbine H, are intion on the aircraft. provides a supply of oil for the bearings.- The oil is pumped from the reservoir 26 to the bearings 23, 24 and 25 by means of the turbine-driven pump 2|, which is preferably .of the constant displacement type, its output depending only upon the speed of rotation of the turbine.

Referring to Fig. 2,the lubrication system for bearings 23, 2t and 25 may be traced as follows: Oil from the reservoir 26 flows through a pipe 21 to the inlet of pump 2| and then through a. pipe 28 connected to the outlet of the pump. The oil, now under pressure, flows through a cooler 29, which may be built into the front end of the ing into the flow passage Ill. The oil, on leaving 'the cooler 29, flows through pipe 3| to the several bearings 23, 24 and 25. I

As a precautionary measure, a pressure relief valve 32 may be provided so that the oil may flow directly from the pump 2| to the pipe 3| to insure lubrication of the bearings in the event flow is sluggish through the cooler.

A second pressure relief valve 33 controls a by-pass 34 'to return oil to the reservoir in the event a dangerous pressure exists in the pipe 28.

The oil leaves the bearings 23, 24 and 25 through their respective pipes 35, 36 and 31 which are connected to. scavenging pumps 38, 39

- and 4|, respectively. The scavenging pumps return the oil to the reservoir 28 through a common pipe 42.

' The scavenging pumps 88, 38 and 4| as well as a pressure pump 48 are shown as separate units bearings 28, 24 and 25, pipe 3| and the cooler 28 to prevent oil from leaking, during standby. from the bearings to the flow passage i2, with the result that the fire hazard is minimized when stopping or starting the plant.

The pressure pump 48 draws oil from the reservoir 28 through a pipe 48, a valve 41, which is open while the plant is running, and a pipe 48, and discharges this oil through a pipe 48 into the pipe 28 leading from the outlet of pump 2!. The-motor 45 is started at the time the power plant is put into operation so that the pump 48 insures immediate delivery or oil to the bearings, it being borne in mind that the pump 2| is driven directly from the shaft 22 of the turbine and compressor and, therefore, is of little or no eil'ect until the turbine reaches hali' speed. The supply of oil from pump 48 is aided by the simultaneous operation of the scavenging pumps 88, 88 and 4| which reduce the pressure in the bearings and their oil supply pipes.

Operation 01' the motor 48 is governed by a control switch mechanism. generally indicated 5|, shown in the schematic diagram of Fig. 2 and located at a convenient position for the operator of the plant. In Fig. 2, the system is shown in its oii"' position, that is, the power plant is idle. When 'the operator starts the plant in the usual manner he also depresses a spring-biased "start button 52 of the switch mechanism 5| causing it to engage and slide a cam block 58 carried on anrarmature 54 of a solenoid 55 to the left, as viewed in Fig. 2, a distance sumcient to bring a contact 58 insulatedly mounted on the armature 54 into engagement with a fixed contact 51. This position of the block 53 and contact 58 is shown by dotted line 58,. and it will he noted that a circuit is completed for the motor 45. The motor circuit may be traced from one side 01' a battery 58, conductor 8|, closed contacts 5M1, conductor 82 to one side of the motor 45, from the other side of the motor through a conductor 53 to the other side of the battery. The motor now runs continuously to drive the pumps 38, 88, 4i and 43, the three former pumps scavenging the bearings and the pressure pump 43 supplying oil under pressure to the bearing supply pipe 28.

When the operator stops the power plant, he also depresses a spring-biased, stop button 84 of the switch mechanism 5! which moves the cam block 53 still farther to the left to the dotted line position 55, so that the contact 55 engages a fixed contact 66 as well as the fixed motor contact 51. Thus, the motor continues to operate and a second circuit is completed for setting a timing mechanism, generally indicated 61, which permits the scavenging pumps to operate for a predetermined interval after shut-down of the power plant. This second circuit may be traced from one side of the battery, conductor 58, the winding of a solenoid 58, closed contacts 2,402,467 gr; 5 2; J I

8856 and conductor 8| to the other side of the battery. 1 a

The movable core 1| of the solenoid 58 is connected to valve stem 12 of valve "in the inlet pipe '46 of the pressure pump 43 so that when the solenoid is energized, upon completion of the circuit just traced, the valve 41 is closed and oil is no longer pumped to the bearings by the pump43. 3 i

The valve stem 12 has fixed thereto an arm 18 insulatedly carrying a contact 14 connected by a flexible conductor 15 to oneside oi the battery 58; The contact 14 slides across a fixed contact 18 as the armature 1i is retracted by energization of the solenoid 68 to momentarily complete a circuit for a clock setting solenoid 11. This circuit may be traced from one side of the battery through conductor 15-, momentarily closed contact 14-46, conductor 18, through the winding 0! solenoid 11, a fixed resistance 18, flexible conductor 8|, closed contacts 82 and 83, and conductor 84 .to the other side of the battery. This circuit is completed only momentarily since the contact 14 carried by the valve stem 12 merely slides across the contact 18 and is disengaged therefrom before engaging a fixed contact 85.

Completion of the circuit Just traced energizes the winding of solenoid 11 and retracts its core 88. The core 88 is fixed to one end of a pivoted arm 81 which also carries the contact 82 and swings this arm from its full line position to its broken line position, indicated 88, separating contacts 82 and 83 to deenergize the circuit for solenoid 11. The opposite end of the arm 81 is connected to a tension spring 88 and provided with a pawl 9| which engages teeth 82 formed on a disc 83 of the clock escapement mechanism (not shown). tarily energized the clock mechanism is wound to run a predetermined interval, which may be of the order oi! three minutes, before contacts 82 and 83 are again closed.

While the clock is running no oil is pumped to the bearings but the scavenging pumps 38, 38 and 4i continue to return oil from the bearings and cooler to the reservoir 26. However, when the clock runs down, the arm 81 is again in its full line position and the contacts 82 and 83 engage completing a circuit for the solenoid 55. This circuit may be traced from one side of the battery, conductor 15, closed contacts 14--85, conductor 84, winding of solenoid 55, conductors and 8|, closed contacts 8283, and conductor 84 to the other side of the battery.

Upon energization of the solenoid 55, its core 54 is retracted and restores the cam block 53 and contact 56 to its original full line position of Fig. 2 separating contacts 58, 51 and 66. Separation of contacts 5851 interrupts the motor circuit and stops pumps 38, 39, 4| and 43. Separation of contacts 5666 deenergizes the solenoid 58 and permits the valve 41 to reopen ready for restarting of the gas turbine power plant.

It will be seen that the scavenging pumps 38, 38 and 41 operate for a predetermined interval after the gas turbine plant is shut down, and remove the oil from the bearings and supply pipes during which interval the flow of oil to the pressure pump 43 is interrupted by the closing of the valve 41.

In Fig. 3, there is shown a modification oi the invention, where, instead of employing a shutoff valve 41 in the inlet pipe 48 of the pump 43 a three-way valve 86 is provided in the pump discharge pipe 48. The valve 85 is arranged to Thus, when the solenoid 11 is momenby-pass oil from the pressure side of the pump 0 to the reservoir 26 during the scavenging period following shut-down of the power plant. In this modification the operation of the solenoid 89 and contacts 14, I6 and 85 is identical with that described above, but when the solenoid 89 is energlzed, the valve 96 is moved from its by-pass closing position shown in full lines in Fig. 3 to its dotted line position where it closes the pipe 49 and opens the passage into a by-pass pipe 91 which returns the oil to the reservoir 26. Thus during the scavenging period the pump 43 is pumping oil, but this oil is immediately returned to the reservoir.

While the invention has been shown in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof, and it is desired, therefore, that only such limitations shall be placed thereupon as are specifically set forth in the appended claims. a

What is claimed is:

1. In a gas .turbine provided with one or more bearings, a pump driven by the turbine for supplying lubricating oil to the bearings, suction means for draining oil from the bearings, and means for operating the suction means a desired time interval aftershutting down the turbine.

2. The combination as claimed in claim 1 with an auxiliary pump to prime the bearings with oil.

3. A gas turbine power plant or the like having one or more bearings, means for supplying oil to said bearing including a pump driven by said turbine, means including a scavenging pump for removing oil from said bearing while the turbine is in operation, an electric motor for driving said scavenging pump, a switch controlling the ener-. gization of said motor, and timing mechanism adapted to be set when said turbine is stopped and to open said switch a predetermined time thereafter so that said motor continues to drive said scavenging pump for a predetermined time. after the supply of oil to said bearing has been shut off, to remove oil from said bearing.

4. A lubricating and scavenging system for a bearing comprising anoil reservoir, means "for pumping oil from said reservoir to the bearing, means for continuously withdrawing oil from said bearing, said last-mentioned means including a scavenging pump, means for driving said pump, timing means for maintaining said scavenging pump in operation for a predetermined interval following the termination of the supply of oil to the bearing to scavenge oil from the bearing whereby leakage during an idle period is prevented. v

5. An. oil scavengingsystem for a gas turbine power plant or the like comprising a scavenging pump adapted to be connected to the lubricating oil outlet of a bearing for continuously withdraw= ing oil from said bearing while the plant or'the like is in operation, means for driving said pump, and time control mechanism for maintaining said pump driving means in operation for a predetermined interval after said plant or the like has been shut down to scavenge lubricating oil from said bearings and thereby prevent said oil from leaking therefrom during a shut-down period.

6. A lubricating system for a gas turbine power plant or the like having one or more bearings, comprising an oil-reservoir, means for supplying oil under pressure to one or more bearings,

means including a pump for, scavenging oil from oil reservoir, means for supplying oil under pressure from said reservoir to said bearing, and meansfor removing the oil from the bearing, said last-mentioned means'including a scavenging pump, means for driving said pump, means for stopping the supply of oil to' the bearing. and means for driving said scavenging pump for a predetermined period after said supply of oil has been stopped, to scavenge oil from said bearing.-

8. A lubricating system for a gas turbine power plant or the like having one or more bearings, comprising anoil reservoir, an oil pumping unit including a pressure pump for supplying oil from said reservoir to said bearing and a scavenging pump for removing oil from said bearing, means for driving said unit. valve means for controlling the flow of oil from said reservoir to said bearing, means for actuating said valve means to shut off the supply of oil to said bearing, and means controlled by the actuation of said valve means for maintaining said scavenging pumpin operation for a predetermined interval to remove all from said bearing and operable at the expiration of said interval to stop said pump driving means and return said valve means to a position for supplying oil to said bearing.

9. A lubricating system for a gas turbine power plant or the like having one or more bearings, comprising an oil reservoir, an oil pumping unit including a pressure pump and a scavenging pump, means for driving said unit, means including a valve connecting the outlet of said pressure pump to the bearing, means for connecting the reservoir to the inlet of said pressure pump, means connecting said scavenging pump to said bearing for removing oil therefrom, said valve means being movable to cut oil the supply of oil to said bearing, and means actuated by the movement of said valve means to cut oil the supply of oil to the bearing for maintaining said scavenging pump in operation for a predetermined interval to remove oil from said bearing and operable at the expiration of said interval to stop said pump driving means and condition said valve to supply oil to said bearing.

10. A lubricating system for a gas turbine power plant or the like having one or more bearings, comprising an oil reservoir, an oil pumping unit including a pressure pump and a scavenging pump, means for driving said unit, means including a valve connecting said reservoir to the inlet of said pressure pump, means for connecting the outlet of said pressure pump to the bearing whereby said pressure pump supplies oil under pressure to said bearing when said valve is open, means connecting said scavenging pump to said bearing for removing oil therefrom, said scavenging pump discharging into said reservoir, means for closing said valve to shut off the supply of oil to said bearing, and means actuated by the closing of said valve for maintaining said scavenging pump in operation for a predetermined interval to remove oil from said bearing and operable at the expiration of said interval to stop said pump driving means and reopen said valve.

11. A lubricating and scavenging system for a 7 or the like. said system comprising an oil reservoir, means including a pump adapted to be driven by said gas turbine power plant for supplying oil under pressure to said bearings for 1u-' bricating the same, means including a scavenging pump for sucking the oil from said bearings and returning the same to said reservoir, means independent of the gas turbine for driving said scavensins pump, and time control mechanism arranged to maintain said independent pump driving means in operation for a predetermined interval following shut down of said gas turbine power plant to scavenge oil from said bearing.

ALBERT S. THOMPSON. 

